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Custom telescope mount using harmonic drives and ESP32

svendewaerhert.com

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Re: Custom telescope mount using harmonic drives and ESP32

#41

Post by donkeybeer »

waerhert wrote: post #38
donkeybeer wrote: post #33

So is the accuracy and stability he achieved better or worse than the commercial mount?

Short answer: it's in the same ballpark as other mounts of the same size. The theoretical accuracy for RA is 0.198″ (65,536 steps and 100:1 reduction) and for DEC is 0.253″ (256*200 steps, 100:1). In practice many things will reduce this accuracy: seeing, proper polar alignment, sturdiness of the wedge and tripod all account for some loss in accuracy. My highest achieved accuracy was probably around 1″ during brief m…

So do you think that complex mechanism ended up no better than the normal mounts? It could be execution too, I am no good at experiments and sometimes even "proven" designs end up a bit subpar, so it could be the design was alright.

Re: Custom telescope mount using harmonic drives and ESP32

#42

Post by stavros »

bongodongobob wrote: post #31
stavros wrote: post #24

This is great! I never understood how people learn how to make solid PCBs, I've made a few things but I think I must be missing some decoupling capacitors or resistors or whatever, because my microcontrollers aren't very stable. How do you all just know what stuff to put on the PCB? Do you read the datasheet for the component and add whatever is there?

Yeah, you have to read the data sheets. Beyond that, use decoupling caps for all power pins, as close to the chip as you can, and make one side of the PCB a ground plane. These 2 things should solve most of your issues.

Excellent, thank you. I already do the plane, but not the caps. Thanks!

Re: Custom telescope mount using harmonic drives and ESP32

#43

Post by waerhert »

dylan604 wrote: post #37
waerhert wrote: post #32

Earlier quoted context omitted.

I estimate a load capacity of 8-10kg. It's not designed for the really big equipment cause I also would like to take it on camping trips. If I were to do this again I will definitely add a threaded hole to mount a counterweight bar. I've noticed the tracking accuracy drop slightly when the mount is in the most overhanging positions.

It looks like you have a typical OTA attached, what camera are you using with that? I've only ever used my DLSR attached to the OTA for prime photography, but it is heavy. I've learned to test the position by hand of the camera through the full rotation to see how the orientation of the camera will change throughout the night to prevent hanging situations and so it has forward tension. I noticed more backlash type is…

I switch between the cheap Byomic 76/700 newton and my Sigma 600mm lens (Canon EF but using an adapter to fit the Olympus body). I tried to get the DSLR looking into the newtonian but it was just too heavy, causing the plastic focuser to simply bend way off axis. I've since bought a dedicated astro camera (Neptune C II) which fits alright on the newtonian. I'm keeping the Byomic 76 only for visual observations now. Looking to buy a proper refractor of around 480mm. The Sigma 600 does alright with the DSLR but isn't very sharp, hard to focus and suffering from some coma. It's good enough to learn the ropes for now.

Re: Custom telescope mount using harmonic drives and ESP32

#44

Post by Aurornis »

consp wrote: post #34
Aurornis wrote: post #29

Earlier quoted context omitted.

Honestly it’s useful enough that I’d pay the several hundred dollars per year if I had to. It’s that much better. The money spent would be well worth it (for me) for all the time saved over using FreeCAD. I’ve used multiple professional CAD packages and I’m just not interested in going back. People sneer and tell me I’m going to get burned some day, but meanwhile I’ve been using it to great effect for many years for…

I'm not going to agree to any of the "free" (you sign away all rights to the things you made free) tiers. Not that anyone would ever use my things but it's out of principle. FreeCAD has issues but is good enough for most people. And once you want to do really complicated things and also can cope the hundred of euros per years fine, but don't complain other people should do the same because you can.

> (you sign away all rights to the things you made free) tiers.

Do you have a source for this? Or are you speculating?

> but it's out of principle

Great that it works for you. I have limited time for hobbies and I can’t justify making choices based on principle to avoid hypotheticals that even you admit aren’t going to happen.

> but don't complain other people should do the same because you can.

I’m not complaining. Anyone who wants to use a certain software based on principle is free to do so.

I’m sharing recommendations from my own experience and that of my peers. If the goal is to focus on the project you’re trying to do instead of fighting with software then people should be aware of their options.

Re: Custom telescope mount using harmonic drives and ESP32

#45

Post by waerhert »

donkeybeer wrote: post #41
waerhert wrote: post #38

Earlier quoted context omitted.

Short answer: it's in the same ballpark as other mounts of the same size. The theoretical accuracy for RA is 0.198″ (65,536 steps and 100:1 reduction) and for DEC is 0.253″ (256*200 steps, 100:1). In practice many things will reduce this accuracy: seeing, proper polar alignment, sturdiness of the wedge and tripod all account for some loss in accuracy. My highest achieved accuracy was probably around 1″ during brief m…

So do you think that complex mechanism ended up no better than the normal mounts? It could be execution too, I am no good at experiments and sometimes even "proven" designs end up a bit subpar, so it could be the design was alright.

Not sure what you mean with complex mechanism. The mount has a similar architecture to other commercially available mounts like the HEM15 iPolar for example.

Re: Custom telescope mount using harmonic drives and ESP32

#46

Post by alnwlsn »

waerhert wrote: post #18
fusslo wrote: post #5

I've been using freeCAD for about 3 years now. Looking at what he was able to make with it blows my mind. I love freeCAD, but I don't think I've ever been so continuously frustrated by a piece of software

Though very grateful for projects like FreeCAD, I did encounter a fair bit of frustration while designing this. Especially random crashes, which only got worse as the project got more complex. As far as usage goes, it's mostly a matter of knowing how to do things in FreeCAD. I haven't encountered anything I could not achieve in FreeCAD. Having no experience in other CAD software probably helped sticking to it.

I came to FreeCad with some years background in Inventor, NX and SolidWorks. The jump from any of these to FreeCAD is not very big; you're doing a lot of the same things. But, most of the problems FreeCad has are solved in those, so you can sort of do anything in them and be none the wiser. In FreeCAD, you need to think a little bit more on how it's going to do things.

But most people don't learn the big CADs first, they learn Fusion. The few times I've tried Fusion, it's given me a headache. It's probably a bigger headache going the other direction.

Then, there are those who do all their CAD work in OpenSCAD. They scare me.

Re: Custom telescope mount using harmonic drives and ESP32

#47

Post by bhouston »

You could sell kits for this btw. There would be demand. And I think you could be quite successful.

The reason is that Trump is tariffing the hell out of the main Chinese telescope accessories manufacturer, ZWO. So if you can provide a non-Chinese alternative....

Think of trying to be Prusa 3D solution in the astrophotography area.

Re: Custom telescope mount using harmonic drives and ESP32

#48

Post by waerhert »

alnwlsn wrote: post #46
waerhert wrote: post #18

Earlier quoted context omitted.

Though very grateful for projects like FreeCAD, I did encounter a fair bit of frustration while designing this. Especially random crashes, which only got worse as the project got more complex. As far as usage goes, it's mostly a matter of knowing how to do things in FreeCAD. I haven't encountered anything I could not achieve in FreeCAD. Having no experience in other CAD software probably helped sticking to it.

I came to FreeCad with some years background in Inventor, NX and SolidWorks. The jump from any of these to FreeCAD is not very big; you're doing a lot of the same things. But, most of the problems FreeCad has are solved in those, so you can sort of do anything in them and be none the wiser. In FreeCAD, you need to think a little bit more on how it's going to do things. But most people don't learn the big CADs first,…

Haha, the thought of using OpenSCAD briefly crossed my mind when I found out about it but I didn't want this project to take a year extra to complete. I do consider exploring some of the other CAD alternatives though if budget permits.

Re: Custom telescope mount using harmonic drives and ESP32

#49

Post by waerhert »

ddahlen wrote: post #3

This is really impressive! I considered buying a big harmonic drive mount for my scope, but the cost is really prohibitive. I have experienced the pain of getting ekos/kstars/indi tools to work well on my personal scope. If you want to try driving indi devices via python I have some python code (it's not super polished, but it does enough for my needs): https://github.com/dahlend/contindi

Cool project. What prompted you to write this? Asking because EKOS already has pretty good scheduling features (I've seen, not used). Along the way I did vibe-code a TUI for controlling the INDI server running on the MeLE 4C minicomputer attached to the telescope: https://www.svendewaerhert.com/content/blog/telescope-mount/... - I switched to a headless setup using a remote indi server after having a bad experience with reliability using remote desktop in Gnome. I'll probably put this TUI on Github once I clean it up a bit.

Re: Custom telescope mount using harmonic drives and ESP32

#50

Post by waerhert »

HorizonXP wrote: post #22

Amazing project and write up, very good timing too! I’ve been into amateur astronomy since I was 13, owning a few telescopes and spending many hours with family at star parties. This week I pulled out our big Meade 10” SCT and our small Meade 4” Newtonian to show my 7yo son the moon and Saturn from my parents Bortle 8 backyard. It was wonderful seeing his awe and surprise, and the fact that my parents were there to s…

Thanks! If you hook your ZWO up to Kstars/EKOS you can use plate-solving in software to find out exactly where your scope is pointed at and then adjust accordingly.
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